Răspuns:
2Ca+O2---> 2CaO
CaO+H2O---> Ca(OH)2
Ca(OH)2+2HCl----> CaCl2 +2H2O
M,Ca(OH)2=(40gCa+2gH+32gO)/mol= 74g/mol
74g hidroxid.....40gCa......2gH....32gO
100G...................X....................Y............Z
X=54%Ca
y=2,7%H
Z=43,3%O
Explicație: